Latex allergy in the workplace

While less than 1% of the general population is sensitized to latex, the U. S. Occupational Safety and Health Administration estimates that 8-12% of he alth-care workers are sensitized. The major source of workplace exposure is powdered natural rubber latex (NRL) gloves. NRL is harvested from Hevea br asiliensis trees and ammoniated to prevent coagulation resulting in the hyd rolysis of the latex proteins. Prior to use in manufacturing, the latex is formulated by the addition of multiple chemicals. Thus, human exposure is t o a mixture of residual chemicals and hydrolyzed latex peptides. Clinical m anifestations include irritant contact dermatitis, allergic contact dermati tis (type IV), and type I immediate hypersensitivity response. Type I (IgE- mediated) NRL allergy includes contact urticaria, systemic urticaria, angio edema, rhinitis, conjunctivitis, bronchospasm, and anaphylaxis. Taking an a ccurate history, including questions on atopic status, food allergy, and po ssible reactions to latex devices makes diagnosis of type-I latex allergy p ossible. To confirm a diagnosis, either in vivo skin prick testing (SPT) or in vitro assays for latex-specific IgE are performed. While the SPT is reg arded as a primary confirmatory test for IgE-mediated disease, the absence of a U.S. Food and Drug Administration-licensed Hevea brasiliensis latex ex tract has restricted its use in diagnosis. Serological tests have, therefor e, become critically important as alternative diagnostic tests. Three manuf acturers currently have FDA clearance for in vitro tests, to detect NRL-spe cific IgE. The commercially available assays may disagree on the antibody s tatus of an individual serum, which may be due to the assay's detecting ant i-NRL IgEs to different allergenic NRL proteins. Sensitized individuals pro duce specific IgE antibody to at least 10 potent Hevea allergens, Hev b l-H ev b 10, each of which differs in its structure, size, and net charge. The relative content and ratios of Hevs in the final allergen preparation most probably could effect diagnostic accuracy. The Hev proteins have been clone d and expressed as recombinant proteins. Sequencing demonstrates both uniqu e epitopes and sequences commonly found in other plant proteins. Sequence h omology helps to explain the cross reactivity to a variety of foods experie nced by latex allergic individuals. The development of recombinant allergen s provides reagents that should improve the diagnostic accuracy of tests fo r latex allergy. Although clinical and exposure data have been gathered on the factors affecting response in latex-allergic individuals, less is known regarding the development of sensitization. Coupled with in vitro dermal p enetration studies, murine models have been established to investigate the route of exposure in the development of latex sensitization. Time-course an d dose-response studies have shown subcutaneous, intratracheal, or topical administrations of non-ammoniated latex proteins to induce IgE production. Both in vitro penetration and in vivo studies highlight the importance of s kin condition in the development of latex allergy, with enhanced penetratio n and earlier onset of IgE production seen with experimentally abraded skin . The diagnosis of latex allergy is complicated by these variables, which i n turn hinder the development of intervention strategies. Further epidemiol ogical assessment is needed to more explicitly define the scope, trends, an d demographics of latex allergy. Diagnostic accuracy can be improved throug h greater knowledge of proteins involved in the development of latex allerg y, and better documentation of the presently available diagnostic tests. In vivo and in vitro models can elucidate mechanisms of sensitization and p rovide an understanding of the role of the exposure route in latex allergy- associated diseases. Together, these efforts can lead to intervention strat egies for reducing latex allergy in the workplace.